Silly me. Not "shower," but shore power. I should have proofread my question better.
Yes, our water pump worked with the battery on. It is only the 12 volt lights that did not work. The KOA campground manager used a digital voltmeter (I think that is what it was) and said everything was ok.
It is only the lights that are a problem. The microwave showed power, although we didn't use it. We didn't try any other 120 volt appliances either.
I did contact the service dept. at RoadTrek and, if I understand them correctly, they said that if the shore power is properly hooked up, then we still have to have the battery turned on to use the lights. That is because the lights run only from battery power and not from shore power. However, I am virtually certain (although I wouldn't bet body parts on it) that when we had the shore power connected we also had the battery turned on & the lights wouldn't work. That doesn't make sense, but I think that is what we tried. Thank you all of you RVers out there that are responding to my plea for help!